The flash player was unable to start. If you have a flash blocker then try unblocking the flash content - it should be visible below.
Actually if you read the paper the authors indicated that only 13% of respondents had NEVER used a stimulant during their career. All the rest admitted to using a stimulant of some source of which the majority were caffeine users.
This of course makes more sense as we all know that ED MDs are useless without coffee
What you do matters.